The invention relates to a safety ski binding, in which the ski boot is held onto the ski by an extensible retraction device, which on exceeding a predetermined releasing force is extended counter to a restoring force, whereby the boot is to a certain extend removed from the ski.
The advantage of the so-called retraction binding is that after extension has taken place, for example, in the case of a fall, the ski boot is automatically drawn to the ski again where it is secured. Thus, after a fall, the time-consuming re-strapping of the ski, as is necessary with conventional safety ski bindings, is consequently unnecesssary. However, it is a disadvantage with the known retraction bindings that the releasing force is substantially maintained throughout the entire extension process and that, due to the constant connection between boot and ski, accidents can still occur despite the given possibility of extension, e.g.; through the ski getting caught somewhere.
The problem of the invention is therefore to provide a safety ski binding of the type defined hereinbefore which has all the advantages of the retraction binding but which effectively prevents injuries of the skier through the constant connection between ski boot and ski.
According to the invention, this problem is solved in that, on reaching the full extension length, the connection between ski boot and ski is broken. In general, the full extension length is not reached on falling so that generally the advantages of the retraction binding, namely more particularly the immediate restoring of the connection between ski boot and ski are fully maintained. However, in the case of an extreme fall the retraction device will become fully extended and, according to the invention, the connection is broken. the skier is now completely free from the ski and consequently cannot be injured through the ski boot remaining secured to the ski.
So that after separation of ski boot and ski the ski movement is stopped, according to a preferred embodiment a ski brake is released when the ski boot separates from the ski. Conventional ski brakes can be used for this purpose; however, it is preferably if the release part which becomes effective on full extension of the retraction device, particularly the retraction cable, releases a ski brake. Thus, the part which brings about separation o the ski boot and ski at full extension is in this case used in two different ways.
If the ski boot is fixed to a sole plate which is connected with the ski via the retraction device, the mounting for the ski boot on the plate is appropriately made detachable in the case of a fully extended retraction device. This construction has the advantage that, after the release, the sole plate can immediately be moved back to the ski making the latter ready for reinsertion of the ski boot.
A first embodiment is constructed in such a way that a plunger which can be extended by a cable fixed to one side of the ski is longitudinally displaceably arranged in a longitudinal groove of the plate, said plunger being prestressed to a normal position in which the plate is held on the ski by a spring, and simultaneously serves as the release member for the mounting. In the same way the plunger can optionally also release a ski brake.
In the area of the end of the longitudinal groove, a movable shoulder, prestressed in the retaining direction by a spring, appropriately projects into said groove and serves to release the mounting and optionally also the ski brake.
The mounting is preferably a holding-down device which can be pivoted about a transverse axis and/or a vertical axis which is arranged on the plate and is held on the ski boot sole in detachable manner by means of the shoulder. On inserting the ski boot, the holding-down device can automatically snap into the shoulder as a result of suitably arranged inclined surfaces.
Another embodiment is based on a safety ski binding where a cable drum, whose cable is fixed to the ski and prestressed in the winding-on direction by a spring, is provided on the plate.
In this connection, the invention provides for the mounting of the ski boot on the plate to be detachable in the case of a fully extended cable. A projection is advantageously provided on the cable drum which, when the cable is fully extended, operates a locking lever prestressed in the locking direction and which releases the mounting. The same shoulder or lever can also release a ski brake.
The mounting is also preferably constructed as a holding-down device which can be provided about a transverse axis and on which engages the locking lever.
A further advantageous embodiment is characterised in that a locking lever is provided which, when operated releases the mounting and which is connected with the ski by a unlocking member in such a way that when the cable line is fully extended the unlocking member is placed under tension and throws the locking lever into its release position. The unlocking member is advantageously a helically wound unlocking cable which has a limited length in the normal position, but which in use can be extended to a multiple of its length. In a further embodiment, a toggle-joint holding-down device is connected with an extensible unlocking member whose other end is fixed to the ski in such a way that, with the cable line fully extended, the unlocking member is placed under tension and the toggle-joint holding-down device is opened.
Finally, the invention can also be used with safety ski bindings in which the ski boot is fixed to a sole plate which is connected with the ski via the retraction device. According to the invention, with such bindings the sole plate is detachable from the ski when the retraction device is fully extended.
According to a first embodiment, the plate can be connected via the retraction device with an intermediate plate which in turn is detachably held on the ski with the retraction device fully extended. The retraction device is hereby preferably arranged in the intermediate plate.
Advantageously the retraction device is detached from the ski boot, release plate or intermediate plate in the case of full extension.
If the retraction device has an extendible cable, according to the invention, one of the cable ends is preferably detachably inserted in its mounting in the case of full extension. Thus, with full extension the cable is free from its drum so that the complete separation desired by the invention is in this case achieved in very simple manner.
With ski bindings where a cable drum spring-prestressed in the winding-on direction is provided on the release plate or ski, the invention provides for the drum-side cable end to be terminated by a swivel which is radially inserted in a suitable recess. When in the case of full extension, tension on the cable no longer acts in the peripheral direction but has a substantially radial component, the swivel is released from its recess and the cable end becomes free.
It is particularly advantageous if the retraction device is locked in the released state and is only freed for retraction after eliminating this state. As a result the retraction device which has been freed from tension cannot pull itself in and be extended again by the skier prior to reinsertion of the cable.
Generally a hand lever is provided in order to accommodate release for retraction after reinserting the cable. According to a further embodiment of the invention, to prevent the release for retraction at an inopportune movement, i.e. with the cable end not refitted, the cable drum cooperates with a spring-loaded latch which snaps in when the cable is fully extended and prevents the drum from reversing, whereby appropriately a locking device is provided for the latch which only frees the latch for manual release when the cable end has been refitted in the drum.
According to a further embodiment, a spring-loaded member is arranged in a longitudinal groove provided in a release plate, intermediate plate, ski or boot sole which, via a latch can enter into tension-transmitting engagement with a swivel fixed to one end of the cable but which separates from the swivel when the cable is fully extended. Here again, an automatic locking device is advantageously provided which prevents a snapping back of the slide member after removing the cable.
In the last-mentioned embodiment the slide member can operate a lever for releasing a ski brake in the case of full extension.
According to the invention, a further generally usable embodiment of a safety ski binding in which a cable drum is used in characterised in that the drum has a diameter which varies in the axial direction in such a way that the winding diameter increases in such a way with increasing winding-off that the increasing tension of the restoring spring is compensated or over-compensated. As a result, the retraction force on extension can not only be kept constant but in fact can also ensure that the retraction force desirably tends to decrease with increasing extension .